Question

On the basis of microstructure briefly explain why gray cast iron is brittle and weak in tension

Answer 1

Gray iron is weak and brittle in tension because the tips of the graphite flakes act as points of stress concentration. ...Gray iron--graphite flakes are embedded in a ferrite or pearlite matrix.

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Answer 2

Gray cast iron possess graphitic microstructure. The matrix contains graphite in the shape of flakes. This gives rise to weaker areas in the metal. So, gray cast iron has low tensile strength.

Stress concentration occurs at the tip of these graphite flakes and makes them brittle in nature.

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